Over the last 50 years, numerous polyoxyalkylene containing surfactants and specialty chemicals have been developed for commercial application (see for example Shick, M. J., Nonionic Surfactants, 1967, Marcel Dekker). These materials, in general, have broad utility as emulsifiers, dispersants, lubricants, detergents, antistats, solubilizers, or thickeners in such industries as cosmetic/personal care, household products, textile, paper, I & I, coatings, and resource recovery.
More specifically, silicone containing surfactants are taking on greater importance in the cosmetic industry. The major class of these compounds is made up of a polydimethylsiloxane backbone to which polyethers have been grafted through a hydrosilation reaction. The other class is made up of an ABA block copolymer of polyoxyalkylene (A) and polydimethylsiloxane (B).
Polyoxyalkylene amines are of great importance in the emulsion polymerization industry and in fiber-related industries where static control is important. Their polyoxyalkylene branches are composed of ethylene oxide polymers or block copolymers of propylene oxide and ethylene oxide.
Moreover, alkylpolyoxyalkylenes, polyoxyalkylene block polymers, alkylamidepolyoxyalkylenes and alkylpolyglucosides are of great importance in the detergent industry.
Potentially, all of the above mentioned compounds could be converted to the corresponding carboxylated derivatives. However, only the alkyl- and arylpolyoxyalkylene carboxylates have been commercialized (via the Williamson ether synthesis). These products have enjoyed relative success in such areas as cosmetic/personal care, household products, agricultural formulations, and the like. Accordingly, in view of their apparent usefulness in a variety of applications, a number of research endeavors have been directed to developing a simple, yet selective process for preparing carboxylates of polyoxyalkylene siloxanes and -amines, alkylpolyoxyalkylenes, polyoxyalkylene block polymers, alkylamidepolyoxyalkylenes and alkylpolyglucosides, without appreciable success.
Although many suitable processes are known for preparing the corresponding carboxylates of these materials, none are free of certain disadvantages which make them rather impractical from a commercial standpoint. For example, although polyoxyalkylene amine carboxylates may be prepared by the Williamson synthesis, it has been found that this reaction indiscriminately leads to both N and O carboxymethylation which results in the undesired quaternization of nitrogen atoms. In addition, the carboxylation of alkylpolyglucosides by the oxidation of primary alcohol sites over platinum catalysts with oxygen as the oxidizer has been thus far commercially unattractive due to economics. Furthermore, no one process has proven to be broadly applicable to all classes of these polyoxyalkylene adducts.